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Registered Member #54655
Joined: Thu Mar 19 2015, 05:56PM
Location: BC, Canada
Posts: 82
Hi guys, I am building a rotary gap for a dual MOT system and I am unsure of what electrode material to use. It will be a propeller gap design powered by a beefy microwave oven fan motor. The only tungsten that I have is 1/8 inch diameter but I've used it before on a similar system and it gets red hot after about 15 seconds of run time. my other options are 3/16 brass or 3/16 steel or 1/4 steel. what will work the best?
Registered Member #54655
Joined: Thu Mar 19 2015, 05:56PM
Location: BC, Canada
Posts: 82
I know that tungsten is the best, but the only tungsten that I have is 1/8 inch and it burns away too fast. I don't really want to spend a bunch of money on thicker stuff.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
Have you considered other refractory metals like molybdenum or niobium? Both are often available in useful shapes on ebay. I could sell you some niobium C-103 alloy round rod, 3/8" diameter. Contains a good measure of hafnium -- how cool is that? I think the same form happens to be up on ebay now -- it's sold for "dressing" diamond grinding wheels. My rod cuts easily with a hacksaw, but an abrasive chopsaw wheel makes only a small indentation while the rod gets red hot around the contact area.
One ebay seller has been listing a bunch of niobium-titanium alloy originally made to be superconducting at liquid helium temperature. There are 1/4" diameter rods listed as "stirring rods" for hot crucible contents.
In my unpracticed opinion, RSG electrode tip temperature can be kept down by using a short thermal path to a decent heatsink.
Registered Member #54655
Joined: Thu Mar 19 2015, 05:56PM
Location: BC, Canada
Posts: 82
Because it's a propeller gap I can't have heat sinks close to the tips of the moving electrodes. I'm planning on running 2-3 kVA and I just need to know if 1/8 tungsten, 3/16 brass, or 1/4 steel will work better.
Because it's a propeller gap I can't have heat sinks close to the tips of the moving electrodes. I'm planning on running 2-3 kVA and I just need to know if 1/8 tungsten, 3/16 brass, or 1/4 steel will work better.
You should do an experiment with these 3 materials :) This forums sees lots of questions like this and I'm sure people would be curious to see some results in detail
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RSG Electrode Material
